Questions tagged [icommand]
Interface for MVVM scenarios in Silverlight and WPF to bind commands from models to controls (Buttons).
icommand
487
questions
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Command for WPF TextBox that fires up when we hit Enter Key
It is very easy to bind Buttons in WPF apps to Commands in a VIEWMODEL class. I'd like to achieve a similar binding for a TextBox.
I have a TextBox and I need to bind it to a Command that fires up ...
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votes
4
answers
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views
ICommand MVVM implementation
So in this particular MVVM implementation I'm doing, I need several commands. I really got tired of implementing the ICommand classes one by one, so I came up with a solution, but I don't know how ...
- 25.8k
56
votes
1
answer
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views
Unit-Test project fails to build after installing .NET 4.5
I have a WPF solution in .NET 4.0 that includes a Unit Test project which tests the different commands used in the ViewModels. Everything was working fine, but then I installed .NET 4.5 and VS2012.
...
- 8,042
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votes
2
answers
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views
ICommand vs RoutedCommand
Let's have a button Command property bound to a custom command.
When should I implement ICommand and when derive from RoutedCommand? I see that RoutedCommand implements ICommand.
In which case could ...
- 12.2k
45
votes
5
answers
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views
Is Josh Smith's implementation of the RelayCommand flawed?
Consider the reference Josh Smith' article WPF Apps With The Model-View-ViewModel Design Pattern, specifically the example implementation of a RelayCommand (In Figure 3). (No need to read through the ...
- 43.7k
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votes
3
answers
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views
What is the actual task of CanExecuteChanged and CommandManager.RequerySuggested?
I got the following code from Josh Smith's MVVM tutorial.
Can anyone provide a quick explanation of what this code actually does?
public event EventHandler CanExecuteChanged
{
add { ...
- 2,721
35
votes
4
answers
173k
views
Pass command parameter to method in ViewModel in WPF?
I am trying to pass CommandParameter to the method in my ViewModel.
How to do this?
private void Open(object sender)
{
if (sender==this.objMainWindow.btnHistory)
{
objMainWindow....
- 497
34
votes
7
answers
23k
views
CommandManager.InvalidateRequerySuggested() isn't fast enough. What can I do?
Short Version
Calls to CommandManager.InvalidateRequerySuggested() take far longer to take effect than I would like (1-2 second delay before UI controls become disabled).
Long Version
I have a ...
- 26.2k
27
votes
2
answers
33k
views
CanExecuteChanged event of ICommand
Icommand contains two methods and one event.
What the two methods do is clear, but I can’t understand what the event does that is provided in ICommand.
When is the CanExecuteChanged event raised?
...
- 3,238
22
votes
2
answers
44k
views
Pass command parameter from the xaml
I try to do something like this:
<DataGrid Name="myGrid" ItemSource="{Binding Path=MyCollection}">
<DataGrid.ContextMenu>
<ContextMenu>
<MenuItem
...
- 1,009
21
votes
7
answers
31k
views
binding a command inside a listbox item to a property on the viewmodel parent
I've been working on this for about an hour and looked at all related SO questions.
My problem is very simple:
I have HomePageVieModel:
HomePageVieModel
+IList<NewsItem> AllNewsItems
+...
- 19.4k
21
votes
2
answers
6k
views
What replaces CommandManager in WinRT?
I'm getting started with Metro style applications (I know we're not supposed to call it Metro, but I can never remember what it's supposed to be called...), and I'm implementing a DelegateCommand ...
- 290k
20
votes
2
answers
44k
views
Multiple command parameters wpf button object
How can I send multiple parameters from Button in WPF? I am able to send single parameter which is value of TextBox properly. Here is the code.
XAML
<TextBox Grid.Row="1" Height="23" ...
- 3,261
17
votes
2
answers
22k
views
How can I pass the event argument to a command using triggers?
So I have a simple setup, an autocompletebox with its Populating event that I want to bind to a command. I use
clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity
(is ...
- 19.4k
17
votes
4
answers
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views
How to cancel window closing in MVVM WPF application
How can I cancel exiting from particular form after Cancel button (or X at the top right corner, or Esc) was clicked?
WPF:
<Window
...
x:Class="MyApp.MyView"
...
/>
<Button Content="...
- 1,161
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votes
3
answers
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views
How do I unit test an async ICommand in MVVM?
I've been Googling and even Bing-ing and I haven't come up with anything that is satisfying.
I have a ViewModel which has some commands, such as: SaveCommand, NewCommand and DeleteCommand. My ...
- 704
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votes
3
answers
3k
views
Translation of C# ActionCommand:ICommand into VB.net
I found a C# class ActionCommand, that implements ICommand and bases on delegates for Execute and CanExecute. Looks perfect for me so far.
public class ActionCommand : ICommand
{
private ...
- 4,557
14
votes
6
answers
63k
views
How to Bind a Command in WPF
Sometimes we used complex ways so many times, we forgot the simplest ways to do the task.
I know how to do command binding, but i always use same approach.
Create a class that implements ICommand ...
- 4,537
14
votes
1
answer
15k
views
How to enable a Button with its CanExecute method
I am developing an application in WPF using MVVM, but I am stuck with the ICommand objects.
I have a windows which contains some buttons, so, I bind them to their respective ICommand in XAML as below:...
- 3,256
13
votes
3
answers
19k
views
wpf command parameter from other object
I'm wondering how to mark up the XAML for the following. I have a view model with an object based on ICommand.
I have a form with a textbox and a button. The button is hooked to the ICommand object ...
- 47.9k
13
votes
5
answers
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views
WPF ViewModel Commands CanExecute issue
I'm having some difficulty with Context Menu commands on my View Model.
I'm implementing the ICommand interface for each command within the View Model, then creating a ContextMenu within the ...
- 1,136
13
votes
2
answers
7k
views
Bind a button to a command (Windows Phone 7.5)
I'm working on my windows-phone app which uses some simple data binding. I've already created a app which was based on the MvvM programming method.The app i'm currently working on also works by MvvM ...
- 1,430
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votes
5
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17k
views
Relay Command can execute and a Task
i want to start a task when a relay command is called, however i want to disable the button as long as that task is running
take this example
private ICommand update;
public ICommand Update
{...
- 3,705
12
votes
1
answer
12k
views
Async ICommand implementation
I'm facing a strange behavior by my asny ICommand implementation when I tried to disable the command while it's executing by default (even when no CanExecute predicate was passed to it).
public bool ...
- 741
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votes
6
answers
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views
WPF: TreeViewItem bound to an ICommand
I am busy creating my first MVVM application in WPF.
Basically the problem I am having is that I have a TreeView (System.Windows.Controls.TreeView) which I have placed on my WPF Window, I have ...
- 3,307
11
votes
7
answers
19k
views
C#/WPF: KeyBinding not triggering Command
I have declared <InputBindings>
<UserControl.InputBindings>
<KeyBinding Key="C" Modifiers="Ctrl" Command="{Binding CopyImageCommand}" />
<KeyBinding Key="V" Modifiers="...
- 85.8k
10
votes
3
answers
17k
views
ICommand Dependency Property
I have an UserControl with a button inside. This button needs to add some items to a Grid that's inside said UC. I'm aware I can do this with a Click event.
The issue here is I am using MVVM and ...
- 723
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votes
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6k
views
ICommand.CanExecute being passed null even though CommandParameter is set
I have a tricky problem where I am binding a ContextMenu to a set of ICommand-derived objects, and setting the Command and CommandParameter properties on each MenuItem via a style:
<ContextMenu
...
- 37.4k
10
votes
1
answer
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views
WPF & MVVM: Get values from textboxes and send it to ViewModel
I'm trying to get the value of two Texboxes (I'm simulating a login window) when I press a button. The command assigned in the button fires correctly, but I don't know how to get the value of the ...
- 789
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votes
4
answers
501
views
What is the real advantage of keeping code out of the XAML code behind?
There is a lot of effort in the Silverlight community to keep a XAML's code behind file as free of code as possible. What is the real motivation behind this?
For example, what is the advantage of ...
- 61.4k
9
votes
2
answers
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views
WPF/MVVM: Disable a Button's state when the ViewModel behind the UserControl is not yet Initialized?
I have a DocumentListView.Xaml with a ListBox and 3 Buttons.
Behind that UserControl sits a DocumentListViewModel with 3 Buttons and their Command Property bound to 3 RelayCommands.
I have 3 ...
- 20.9k
9
votes
3
answers
2k
views
Should I check an ICommand's CanExecute method before calling Execute from procedural code?
When using ICommands in XAML, WPF uses the CanExecute method to enable or disable controls associated with the command. But what if I am calling Execute from procedural code? Should I first check ...
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votes
2
answers
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views
How to bind a Command to double-click on a row in DataGrid
I have developed a WPF UserControl that is intended to be used as a pick list as follows:
A DataGrid bound to a CollectionView of entities (e.g. of Employees)
A TextBox above the DataGrid that can be ...
- 123k
9
votes
1
answer
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views
What comes first - Command or EventHandler?
In context of Microsoft's MVVM pattern and its Commanding/Event Handling aspects consider I am doing both binding a Command to a Control (say a Button) and subscribing to the control's Click event.
...
- 5,846
8
votes
3
answers
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views
WPF and MVVM. Binding Events
I'm developing a WPF application with the MVVM pattern, RelayCommand, etc.
I read a lot on this question but I am not clear as to:
All I want to do is move a shape, like an ellipse, for example, and ...
- 89
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votes
1
answer
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views
Is the common implementation of RelayCommand violating the MVVM pattern?
A very common implementation of RelayCommand seems to include the following lines:
public event EventHandler CanExecuteChanged
{
add
{
CommandManager.RequerySuggested += value;
}
...
- 4,250
7
votes
3
answers
8k
views
WPF MVVM - Unit Testing a command - Private vs Public methods?
Basically, If I use MVVM and expose public ICommands, should my delegates be public or private?
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votes
1
answer
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views
Button Command CanExecute not called when property changed
I have a form with a textbox and a button.
When that textbox has it's value changed, the button command doesn't call the CanExecute method of it's command.
The command parameter is set but doesn't ...
- 439
7
votes
2
answers
3k
views
Are there any performance implications with CanExecuteCommand?
What are the performance implications of using the CanExecuteCommand of the ICommand object. Is the method executed over and over again?
I need to iterate through a collection of about 200 objects ...
- 3,512
7
votes
2
answers
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Saving a WPF canvas as an image following MVVM Pattern
I have a canvas, e.g. similar to this solution or many others using the ItemsControl.
Now I want a button which should be bound to an ICommand. This command should call a method of ViewModel class ...
- 452
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votes
8
answers
6k
views
How to close a ChildWindow with Cancel button using MVVM Light Toolkit
I'm new to MVVM and trying to figure out how to close a ChildWindow with the traditional Cancel button using MVVM Light Toolkit.
In my ChildWindow (StoreDetail.xaml), I have :
<Button x:Name="...
- 379
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votes
1
answer
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views
MVVM Call Command from CommandBinding
I wanted to bind a CommandBinding to a ViewModel ICommand, this way, when the user hits Delete I can trigger my ViewModel's delete logic.
The only way I know how to do it is in code behind, with this:...
- 13.9k
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votes
4
answers
6k
views
What is the reason for ICommand in Mvvm?
In application using a mvvm-approach it's pretty common that the ViewModel provides one or more Command-properties. These properties often have the type ICommand or DelegateCommand or something like ...
- 637
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votes
3
answers
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views
Updated title: Why ICommand.CanExecute is getting called all the time, instead of working like an event?
I am adopting MVVM pattern in WPF and have learned the use of Command. But in my implementation, the delegate I assigned to implement CanExecute is always called. I mean if I put a break point inside ...
- 4,939
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votes
2
answers
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views
MVVM (ICommand) in Silverlight
Please, don't judge strictly if this question was discussed previously or indirectly answered in huge nearby prism and mvvm blogs.
In WPF implementation of RelayCommand or DelegateCommand classes ...
- 1,333
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votes
2
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views
MVVM Execute Command on ViewModel from other ViewModel
I'm struggling for about 14 days now with a simple task: In database, I have definitions for hardware categories. For example :
HDD
Internal
External
Flash
This list is in database defined like ...
- 299
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votes
4
answers
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views
What is the recommended way to open a new window using MVVM in WPF
Hello everyone and thanks in advance for your time.
I'm currently learning MVVM using WPF for a small Biz App that I'm writing. I have read a lot of articles about the MVVM pattern and found that one ...
- 63
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2
answers
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views
Why is my ICommand.CanExecute(object) parameter null when I set CommandParameter to some Binding, but non-null when I set it to some static value?
I'm learning ICommands in WPF and I ran into a problem with some simple code. I have a Button with a Command. If I set the command parameter to a static value like this, CommandParameter="100", the ...
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votes
1
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views
Dotfuscator CE Build Error: External type not found System.Windows.Input.ICommand,PresentationCore
I have an application targeting the .NET Framework 4.0. It builds and runs fine but I cannot get it to compile in Dotfuscator CE and they will not support it since it is CE. I am stuck.
Dotfuscator ...
- 117
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votes
2
answers
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RelayCommand in C#
I am learning MVVM for C# Silverlight development from
http://msdn.microsoft.com/en-us/magazine/dd419663.aspx
and I am confused about the RelayCommand class mentioned in the context. The code is:
...
- 11.2k